leds: leds-qpnp-flash: correct torch enablement and disablement

Current torch enablement setting binds both channels together.
When a user turns on and leaves the other off, there are issues.

Change-Id: I8697f0c104fd32f450d1ae82ac823940d343f3d3
Signed-off-by: Chun Zhang <chunz@codeaurora.org>